PDF《MP3312》

MP3312 2.

7V-5.5V Input , 38V OVP, Dual-Channel White LED Driver MP3312 Rev. 1.02 www.MonolithicPower.com

1 1/13/2015 MPS Proprietary Information. Patent Protected. Unauthorized Photocopy and Duplication Prohibited. ?

2015 MPS. All Rights Reserved. The Future of Analog IC Technology DESCRIPTION The MP3312 is a dual-channel step-up WLED driver with integrated 40V MOSFET, and supports 2.7V to 5.5V power supply input. It uses peak current mode to regulate the LED current which is set by external resistor. The MP3312 employs 1.2MHz fixed switching frequency. It features supporting both PWM input analog dimming and digital analog dimming to accurately regulate the dimming current. The MP3312 integrates current source to balance LED current, which leads good ILED matching and accuracy performance. In addition, the MP3312 has LED open and short protection, cycle by cycle current limit protection, and thermal shutdown protection. It is available in tiny WLCSP1.35x1.35-9 package. FEATURES ? 2.7V~5.5V Input Voltage ? 1.2MHz Switching Frequency ? Dual Channels Support up to 30mA/String ? 1% Current Matching Between LED Channels ? +/-2% Current Accuracy ? 38V OVP Protection ? PWM Input Analog Dimming Mode ? 5kHz to100kHz PWM Input Analog Dimming ? 1-Wire Interface for Digital Dimming ? 9-bit Dimming Resolution ? Internal Soft Start to Reduce Inrush Current ? Available in WLCSP1.35x1.35-9 Package APPLICATIONS ? Feature Phone and Smart Phones ? Tablets ? GPS Receivers ? 20ms shuts down the IC. B2 COMP Internal error amplifier output pin. Connect a capacitor to compensate the system. B3 GND GND pin. C1 EN Enable and 1wire input pin. High logic enables the IC and low logic >

2.5ms shuts down the IC. C2 VIN Power supply input pin. Connect a ceramic capacitor nearby this pin to bypass the IC. C3 SW Drain connection of the internal N-CH power MOSFET. MP3312 - 2.7V-5.5V INPUT, 38V OVP, DUAL-CHANNEL WHITE LED DRIVER MP3312 Rev. 1.02 www.MonolithicPower.com

8 1/13/2015 MPS Proprietary Information. Patent Protected. Unauthorized Photocopy and Duplication Prohibited. ?

2015 MPS. All Rights Reserved. FUNCTIONAL BLOCK DIAGRAM OSC RAMP PWM Control EA PWM Comparator VREF VIN VOUT SW LED1 GND Current Control Feedback Control Min. Max. Short Protection Analog Dimming EN Detection LED2 ISET EN OVP Shutdown PWM COMP EN L1 D1 C1 C2 C3 R1 R2 VIN Figure 1― Functional Block Diagram MP3312 - 2.7V-5.5V INPUT, 38V OVP, DUAL-CHANNEL WHITE LED DRIVER MP3312 Rev. 1.02 www.MonolithicPower.com

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2015 MPS. All Rights Reserved. OPERATION The MP3312 employs the fixed switching frequency, peak current mode control architecture and

2 regulated current sinks to power the LED array. The operation of the MP3312 can be understood by referring to the below function block diagram. System Startup Either pulling EN or PWM to high enables the IC operation while pulling EN to GND for >

2.5ms or pulling PWM to GND for >

20ms shuts down the IC. When enabled, the MP3312 checks the topology connection first. The MP3312 also checks other safety limits, including UVLO and over-temperature protection (OTP). If all the protections pass, the chip then starts boosting the step-up converter with an internal soft-start. It is recommended that the enable signal occurs after the establishment of the input voltage and PWM dimming signal during the start-up sequence to avoid large inrush current. Switching Operation At the start of each oscillator cycle the main low side FET (M1) is turned on through the control circuitry. To prevent sub-harmonic oscillation at duty cycle greater than